tests/docker: allow user to override check target

This is useful when trying to bisect a particular failing test behind
a docker run. For example:

  make docker-test-clang@fedora \
    TARGET_LIST=arm-softmmu \
    TEST_COMMAND="meson test qtest-arm/qos-test" \
    J=9 V=1

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20221117172532.538149-4-alex.bennee@linaro.org>

tests/docker/Makefile.include

@@ -184,6 +184,7 @@ docker:
 	@echo '    TARGET_LIST=a,b,c    Override target list in builds.'
 	@echo '    EXTRA_CONFIGURE_OPTS="..."'
 	@echo '                         Extra configure options.'
+	@echo '    TEST_COMMAND="..."   Override the default `make check` target.'
 	@echo '    IMAGES="a b c ..":   Restrict available images to subset.'
 	@echo '    TESTS="x y z .."     Restrict available tests to subset.'
 	@echo '    J=[0..9]*            Overrides the -jN parameter for make commands'
@@ -230,6 +231,7 @@ docker-run: docker-qemu-src
 			$(if $(NETWORK),$(if $(subst $(NETWORK),,1),--net=$(NETWORK)),--net=none) \
 			-e TARGET_LIST=$(subst $(SPACE),$(COMMA),$(TARGET_LIST))	\
 			-e EXTRA_CONFIGURE_OPTS="$(EXTRA_CONFIGURE_OPTS)" \
+			-e TEST_COMMAND="$(TEST_COMMAND)" 		\
 			-e V=$V -e J=$J -e DEBUG=$(DEBUG)		\
 			-e SHOW_ENV=$(SHOW_ENV) 			\
 			$(if $(NOUSER),,				\

tests/docker/common.rc

@@ -63,12 +63,12 @@ check_qemu()
 {
     # default to make check unless the caller specifies
     if [ $# = 0 ]; then
-        INVOCATION="check"
+        INVOCATION="${TEST_COMMAND:-make $MAKEFLAGS check}"
     else
-        INVOCATION="$@"
+        INVOCATION="make $MAKEFLAGS $@"
     fi
 
-    make $MAKEFLAGS $INVOCATION
+    $INVOCATION
 }
 
 test_fail()